1. Field of the Invention
This invention relates to semiconductor read only memory devices and more particularly to method of coding of a Mask ROM device and the devices produced thereby.
2. Description of Related Art
U.S. Pat. No. 5,002,896 of Naruke for "Mask-ROM Manufacturing Method that Enhances Integration Density" and U.S. Pat. No. 5,200,355 of Choi for "Method for Manufacturing a Mask-Read Only Memory Device" show Mask ROM process/resulting structures, but do not show the LDD coding feature.
In a conventional method of manufacture of a MASK ROM device, at least, one extra process step is required to define a coded device. The extra process step increases the manufacturing process cycle time.